To date there is no effective vaccine for HIV infection. Although a major vaccine trial based on homologous recombinant viral prime/boost failed recently, a study undertaken later, in a monkey model, suggests that with a more appropriate heterologous prime/boost regimen, it is possible to elicit a strong T cell response that protects against virulent viral challenge. Thus, for a vaccine to be effective, it should be able to evoke a strong and broad-based T cell response. Moreover, pretesting the relevance of novel vaccine approaches by HIV challenge in preclinical models would greatly help prevent the agony of vaccine failures in human clinical trials. As Dendritic cells are critical for induction of T cell immune responses, we hypothesize that immunization with HIV proteins targeted to dendritic cells in which select negative immunomodulatory molecules such as SOCS-1, PD-L1, L2 and IL-10 have been suppressed by RNA interference will elicit a potent polyfunctional CD8+ T cell response. Our hypothesis is based on our preliminary results in which silencing of SOCS-1 via targeted siRNA delivery to DC was enough to elicit a robust primary T cell response in vitro to several HIV gag epitopes, including subdominant ones. Moreover, we have recently shown the feasibility of using the latest versions of humanized mouse models to test the efficacy of siRNA mediated interventions in HIV infection and are thus are in a position to test whether the human DC- targeted methods are effective in vivo.
In Specific Aim 1 of this proposal we will develop methods and reagents for targeted delivery of HIV-antigens and immunomodulatory siRNA reagents to human DCs. These will include a DC targeting peptide modified to bind siRNA as well as to deliver HIV antigens, two DC-targeting antibody fused to HIV proteins and further modified to bind siRNAs and a liposomal formulation that allows targeted delivery of siRNA and HIV antigen in mRNA form.
In Aim 2, we will evaluate whether co-delivery of HIV immunogen with the different immunomodulatory siRNA (singly and in combination) by any of these methods is able to induce a broad and polyfunctional primary HIV-specific CD8 T cell response in vitro.
In Aim 3, we will validate the in vitro findings as well as test the efficacy of our methods to actually confer protection from in vivo HIV challenge in the humanized BLT mouse model transgenic for HLA-A2 and HLA-B27.

Public Health Relevance

This project will develop DC-targeted approaches for HIV antigen delivery and RNAi manipulations as a novel HIV vaccine strategy to induce potent virus-specific T cell immunity. If successful the studies would provide an alternative to the recombinant viral vector-based vaccines. In addition, the in vivo studies in a preclinical animal model will provide novel insights into the immune correlates of protection.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI084795-04
Application #
8317541
Study Section
Special Emphasis Panel (ZAI1-SV-A (M2))
Program Officer
Leitner, Wolfgang W
Project Start
2009-09-15
Project End
2014-08-31
Budget Start
2012-09-01
Budget End
2013-08-31
Support Year
4
Fiscal Year
2012
Total Cost
$366,438
Indirect Cost
$86,645
Name
Texas Tech University
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
609980727
City
Lubbock
State
TX
Country
United States
Zip Code
79430
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Bharaj, Preeti; Chahar, Harendra Singh; Alozie, Ogechika K et al. (2014) Characterization of programmed death-1 homologue-1 (PD-1H) expression and function in normal and HIV infected individuals. PLoS One 9:e109103
Manjunath, N; Yi, Guohua; Dang, Ying et al. (2013) Newer gene editing technologies toward HIV gene therapy. Viruses 5:2748-66